Assessment of Voltage Fluctuations for Battery Storage Systems Providing Frequency Response Services^†

Round 1

Reviewer 1 Report

As a reviewer of the article,  Assessment of Voltage Fluctuations for Battery Storage Systems Providing Frequency Response Services, I present the following comments:

 

1. The article presents only theoretical considerations. There is no reference to real disturbances occurring in the power system.

2. Figure 3. Great Britain (Mainland UK) Typical Frequency Data – November 2022 – what is the frequency measurement interval?

3.  For stable operation of the system, a constant value of the voltage frequency is required. In the event of a rapid change in frequency in the power system, the protection of generators in the power plant is activated. The authors in Fig. 5, Fig. 8, Fig. 8 (incorrect designation in the text should be Fig. 9 - line 341) present frequency changes covering a period of 600 s.

Changes in frequency during Blackouts in 2003 in the USA and Italy (Figures below) are very dynamic. Therefore, a basic question arises: How fast frequency changes should be compensated by the method proposed by the authors?

PSERC Blackout of 2003: Description and Responses, Dennis Ray, Executive Director Power Systems Engineering Research Center Updated November 7, 2003 © 2003 Dennis J. Ray

 

General blackout in Italy Sunday September 28, 2003, h. 03:28:00, S. Corsi, C. Sabelli Published 6 June 2004. Physics, IEEE Power Engineering Society General Meeting, 2004.

 

 

4. Another disturbance that the authors write about is voltage fluctuations. The result of voltage fluctuations may be the phenomenon of light flickering. As you know, the visible phenomenon of light flickering is annoying for humans. The main cause of voltage fluctuations are receivers with dynamically changing power consumption (arc furnaces, welding machines, etc.). Fluctuations resulting from the operation of the equipment are characterized by rapid changes in amplitude (about 8-10 changes per second).

The authors in Figure 6 analyze a system with a static load (20MW Static load 1, 20MW Static load 2 and 5MW Eguiv Load 1, 5MW Eguiv Load 1). Such receivers will not generate rapid voltage changes in the network. For this reason, the low level of flicker indicators Table 3 (all three tables in the text have the same numbering).

In the case of compensation for disturbances caused by receivers generating annoying light flickering, the system proposed in the article should react within milliseconds (and several times per second). In my opinion, from the point of view of practical implementation, such a solution will be very difficult and expensive to implement (if it is possible at all).

5. The most doubts are caused by the correct determination of the light flicker indicators (3x Table 3 - editing error in the text - lines 343, 358).

On page 4 - line 140, the authors correctly wrote that the short-term flicker indicator Pst is determined in 10 minutes. The analysis presented in the article in figures 8-10 covers a period of only 600 seconds. How then can the Pst indicator be correctly determined in such a time. In my practice related to the measurements of light flicker indicators in power systems, I have not encountered such Pst values, which are presented in the article.

 

6. The article uses a large amount of screeds (Battery Energy 8 Storage Systems (BESS)). I suggest placing them at the end of the article.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

This paper presents the investigations about voltage fluctuations caused by the operation of Battery Energy Storage Systems that provide Frequency Response  and Fast Frequency Response  services. As a test case is using the Great Britain power system in the United Kingdom. 

The paper proposed a novel systematic approach for assessing voltage disturbance and flicker concerns  using an appropriate control algorithm of slow speed noise generator  and fast speed noise generator and using average filters.

The impact of large Battery Energy Storage Systems in the upstream networks and the impact on all nearby substations connected to the local network and corresponding final consumers have been studied in great detail.

The general idea of the article is good, as it is aimed at solving the infrastructure problems in the mass use of Battery Energy Storage Systems.

Some remarks.

1.     In references, the authors are spelled initially with the last name – references [1,5,6,15].

2.     Conclusions should be revised, it is good to reflect more specifically the results obtained in the exposition of the article.

3.     To provide a definition of "large BESS"

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Comments of this reviewer on the manuscript Electronics-2218789 are as follows:

·       This manuscript proposes a novel approach for assessing voltage disturbance and flicker concerns for BES units using an appropriate control algorithm and a frequency disturbance generator. A representative part of the GB system consisting of the two main busbars is used as a test network/grid, that is, a case study. It is assumed that the BES units are connected to both these busbars, and the following operating regimes are considered: Case 1 – one BES unit is operated at 132 kV Busbar 1, and another BES unit at 132 kV Busbar 2 is set out of service, Case 2 – one BES unit is operated at the 132 kV Busbar 2, and another BES unit at 132 kV Busbar 1 is set out of service, and Case 3 – both BES units are operated at the same time at the 132 kV Busbars 1 and 2. Therefore, the topic of this manuscript should be very useful for practice and interesting for the readership.

·       According to the first sentences of Abstract and Introduction, the Authors used the same abbreviation “BESS” for the terms “Battery Energy Storage Systems” and “Battery Energy Storage Schemes”. The same abbreviation should be used for one term at the level of the entire manuscript, of course, taking into account singular or plural. Then, the term “BESS unit” is used throughout the entire text. In this regard, extracting the part "system unit" from "Battery Energy Storage System Unit" gives a term whose meaning is “unit of a system”. Therefore, this reviewer suggests the use of the term “Battery Energy Storage unit” or “BES unit” instead of the term “Battery Energy Storage System unit” or “BESS unit”, respectively.

·       In the manuscript, the terms “UK GB system” and “GB system” are used, which, according to Abstract, can be assumed to represent the same power system. This must be unified, taking into account that “UK GB” may represent a pleonasm in the context of the country.

·       Keywords should be singular, listed alphabetically and followed by the appropriate abbreviation (if any) in parentheses. Namely: Keywords: Battery Energy Storage (BES) Unit, Frequency Response, Inverter-Based Generation, Voltage Disturbance, and Voltage Stability.

·       There are some grammatical errors and typos in this manuscript. Some examples of them are as follows: “This is concern is influenced by…”, “Secondly, a generic model a of a 2-slope response…”, “…a nominal MVar setpoint…”, “…it is also possible to also operate…”, “…and the magnitudes of the voltage disturbances is also higher…”, “Where there are scenarios where there are multiple BESS units within the same area,…”, etc.

·       The following sentence: “The approach used to create the frequency disturbance is in the method contains an inherent probabilistic component as the frequency disturbance generator is random.” needs to be improved in terms of meaning.

·       The reference list should be improved and expanded in terms of the relevant state-of-the-art.

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

After the correction made in the article by the authors, I suggest publishing the article in electronics